Potential Exposure
Cristobalite is used in the manufacture of water glass, refractories, abrasives, ceramics and enamels. Quartz is used as a mineral, natural or synthetic fiber. Tridymite is used as a filtering and insulating media and as a refractory material for furnace linings. Workers are potentially exposed to crystalline silica in such industries as granite quarrying and cutting, foundry operations; metal, coal, dentistry, painting, and nonmetallic mining; and manufacture of clay and glass products.
First aid
If this chemical gets into the eyes, remove any contact lenses at once and irrigate immediately for at least 15 minutes, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts the skin, remove contaminated clothing and wash immediately with soap and water. Seek medical attention immediately. If this chemical has been inhaled, remove from exposure, begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR if heart action has stopped. Transfer promptly to a medical facility. When this chemical has been swallowed, get medical attention. Give large quantities of water and induce vomiting. Do not make an unconscious person vomit.
Incompatibilities
Violent reactions with powerful oxidizers: fluorine, chlorine trifluoride; manganese trioxide; oxygen difluoride, hydrogen peroxide, etc.; acetylene; ammonia.
Chemical Properties
Silicon dioxide/crystalline silica is a component of many mineral dusts and materials which melts to a glass at very high temperature.
Waste Disposal
Sanitary landfill
Uses
Because of its unique physical and chemical properties, crystalline silica has many uses. Commercially produced silica products include quartzite, tripoli, ganister, chert, and novaculite. Crystalline silica also occurs in nature as agate, amethyst, chalcedony, cristobalite, flint, quartz, tridymite, and, in its most common form, sand (IARC 1997). Naturally occurring silica materials are classified by end use or industry. Sand and gravel are produced almost exclusively for road building and concrete construction, depending on particle size and shape, surface texture, and porosity (IARC 1987).
General Description
Rounded silica sand is the naturally occurring sand usually mined from glacial deposits, sometimes called Ottawa sands. Silica sand is essentially made of quartz (SiO2 ) grains.
Pressure range: 28 < σc < 35 MPa (4 < σc < 5 ksi)
Advantages: Low cost, low density, wide availability, and excellent chemical resistance in acidic media except those containing free HF
Drawbacks: Low permeability, low crushing strength, and poor resistance to flow back
Synthesis
Squartz is silica, the chemical molecular formula for SiO2nH2O, because of its use is similar to carbon black and white, so it is named silica. Silica can be divided into precipitated silica (precipitated hydrated silica) and fumed silica (fumed silica
Carcinogenicity
Respirable crystalline silica, primarily quartz dusts occurring in industrial and occupational settings, is known to be a human carcinogen based on sufficient evidence of carcinogenicity from studies in humans. Respirable crystalline silica was first listed in the Sixth Annual Report on Carcinogens in 1991 as reasonably anticipated to be a human carcinogen based on sufficient evidence of carcinogenicity from studies in experimental animals; the listing was revised to known to be a human carcinogen in the Ninth Report on Carcinogens in 2000.
Toxics Screening Level
The Initial Threshold Screening Level for crystalline silica is 3 μg/m3, with an annual
averaging time. This ITSL applies to quartz (CAS No. 14808-60-7) and three polymorphs:
cristobalite (CAS No. 14464-46-1), tridymite (CAS No. 15468-32-3) and tripoli (CAS No.
1317-95-9).
